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Design considerations of mechanical fragmentation systems for entry development in oil shale.

Larson DA; Olson RC
Proceedings of the 10th Oil Shale Symposium April 21-22, 1977, Golden, Colorado. Reubens JB, ed. Golden, CO: Colorado School of Mines Press, 1977 Jul; :99-119
The Underground Mining Division, Twin Cities Mining Research Center, U.S. Bureau of Mines has conducted research to evaluate bits and cutters of continuous fragmentation machines for oil shale. Laboratory experiments were performed to (1) define fundamental differences in performance of the various bits and cutters and (2) relate inherent advantages of the different cutting tools to entry development in oil shale. In addition, mechanical excavation machines that have potential in oil shale mining are presented. The bit and cutter experiments were performed on oil shale samples from the Mahogany Zone, Parachute Creek Member of the Green River Formation, in the Piceance Creek Basin (Colo.). A linear cutting apparatus was used to load and traverse a bit or cutter across a smooth shale surface; a rotary drill was used for tests with drag bit cutterheads. Graphs of specific energy, chip weight, groove width, and cutting coefficient versus depth; cutting force and depth of cut versus normal force; and specific energy versus penetration rate of drag bit cutterheads are presented. The experiments demonstrated that (1) specific energy decreases with increasing depth of penetration, rapidly at first, then approaching a constant; (2) drag bits are more efficient, and (3) the specific energy for steady fragmentation is about 40 percent of that required for independent groove fragmentation. The benefit of drag bit frag mentation efficiency was demonstrated by comparison calculations for drag bit and disk cutter machines. These comparisons were made using a disk cutter tunnel boring machine, a drag bit tunnel boring machine, and a continuous drum miner. At the same production rate, the drag bit tunnel boring machine required only 12 percent of the thrust and 43 percent of the torque needed by the disk cutter machine. Even though the production rate of the drum miner was 60 percent of that of the other machines, it required only 10 percent of the torque and 20 percent of the thrust needed by the disk cutter tunnel boring machines.
Mining-industry; Underground-mining; Mining-equipment; Cutting-tools
Publication Date
Document Type
OP; Conference/Symposia Proceedings
Fiscal Year
Identifying No.
OP 84-77
NIOSH Division
Source Name
Proceedings of the 10th Oil Shale Symposium April 21-22, 1977, Golden, Colorado
Page last reviewed: October 29, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division